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About the Authors:
Denise Risch
* E-mail: [email protected]
Affiliation: Integrated Statistics, Woods Hole, Massachusetts, United States of America
Peter J. Corkeron
Affiliation: Northeast Fisheries Science Center, Woods Hole, Massachusetts, United States of America
William T. Ellison
Affiliation: Marine Acoustics, Inc., Middletown, Rhode Island, United States of America
Sofie M. Van Parijs
Affiliation: Northeast Fisheries Science Center, Woods Hole, Massachusetts, United States of America
Introduction
The last decade has seen an increased awareness of the impacts of anthropogenic underwater noise on marine mammals. Impacts have been described for several different sources, including seismic airguns [1], [2], underwater explosions [3], construction and pile driving [4], acoustic deterrent devices [5], and scientific and military sonar systems [6]–[9]. Possible effects include lethal injuries, short- or long-term hearing damage, and the disruption of normal behavior, including feeding, mating and communication [10]–[11]. Disruption of communication behavior may include signal modifications, for example changes to signal duration, frequency or amplitude [12]–[14], as well as changes in signal usage, repetition, or the cessation of signaling [15], [16], [13], [9]. Changes in communication behavior have been demonstrated across several baleen whale species and in response to various noise sources [17], [2], [14].
This study investigates the effect of low-frequency pulses on the occurrence of humpback whale song. The pulses were produced by an Ocean Acoustic Waveguide Remote Sensing (OAWRS) experiment, roughly 200 km from the whales. The mobile OAWRS system was used to image fish shoals over a 100 km diameter area [18]–[20].
Male humpback whales (Megaptera novaeangliae) sing long, complex songs on their breeding grounds [21]. In addition, humpback whales have been shown to sing on migration [22] and feeding grounds [23]. On breeding grounds, humpback whales may alter song production in response to boat noise, seismic surveys and military sonar [24], [8], [25], [26].
Most published examples of the effects of non-chronic anthropogenic noise on marine mammals have dealt with sources within kilometers or perhaps tens of kilometers of the study animals [9]. Effects over hundreds of kilometers have seldom been investigated or demonstrated [27].
Arrays of Marine Autonomous Recording Units (MARUs) [28] gathered low-frequency acoustic data within the Stellwagen Bank National Marine Sanctuary (SBNMS) in 2006 and from December 2007–May 2010 [29], [30]. In autumn 2006, these recordings happened...